Steam is a popular game distribution platform by Valve.
Steam requires glibc to run, and thus doesn't straight up run on Alpine Linux. To work around this problem, we'll use Flatpak. Make sure you have the Flathub repository installed.
# apk add flatpak $ flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo $ flatpak install com.valvesoftware.Steam
After installation Steam can be started using it's .desktop file or on the command line:
$ flatpak run com.valvesoftware.Steam
My controllers aren't detected
By default Steam doesn't have permission to read your controllers. This can be fixed by installing an udev rule. The one from rpmfusion's Steam package seems to work well.
$ curl -O https://raw.githubusercontent.com/rpmfusion/steam/master/60-steam-input.rules # install -Dm644 60-steam-input.rules -t /etc/udev/rules.d # udevadm control --reload-rules && udevadm trigger # or reboot